A bicycle transmission is used for changing the ratio between a crank operating speed and a driving wheel operating speed to best meet each particular driving situation. Bicycle transmissions known in the prior art use different size sprockets (chainwheels) and a driving chain to transmit a pedaling force to a driving (rear) wheel. They use two sets of sprockets, wherein one set of sprockets is mounted on a crank spindle and another on a rear axle. The chain rotates on one of the front sprockets and one of the rear sprockets and is displaced by derailleurs from one sprocket to another in order to change the driving wheel operating speed. The front derailleur is located proximate to the front sprockets and used to displace the chain on these sprockets. The rear derailleur is located proximate to the rear sprockets and used to displace the chain on these sprockets.
In order to change the speed, the chain has to be displaced from at least one sprocket which causes interruptions in the power transmitting process and results in power loss. Due to their size and position the chain and sprockets cannot be properly lubricated without creating negative effects and are often exposed to environmental damage. The transmissions of the prior art do not allow an identical ratio of speed increase/decrease between two neighboring speeds, thereby creating negative effects regarding power flow. A rear set of sprockets (cogs' cassette) requires both chainstays and seatstays to be spaced wide apart to accommodate for the width of the sprockets which, in turn, creates negative aerodynamic effects. In sum, the transmissions of the prior art do not enable an efficient and uninterrupted flow of the pedaling force and negatively influence the aerodynamic properties of the bicycle.